A Hybrid no Frost Refrigeration System Using a Membrane Based Desiccant System
Résumé
Frosting is a major problem in refrigeration systems and its accumulation on the evaporator of a vapor
compression cycle deteriorates the coil’s performance. In some applications, frost is avoided by
dehumidifying the air using solid desiccant wheels which are regenerated usually through electrical means
causing high energy consumption. Thus the use of liquid desiccants that offer easier energy integration
allows proposing a hybrid system where the desiccant regeneration is done by the waste thermal energy
from the condenser of the compression cycle. The system’s dehumidifier consists mainly of a membrane
based heat and mass exchanger necessary to prevent the escarpment of the desiccant solution droplets to
the air avoiding corrosion problems. This paper proposes a model of such a membrane exchanger to derive
sensitivity analysis of the key design parameters. Three architectures are studied where in the first
architecture the desiccant solution only dehumidifies the air while the evaporator does the entire cooling. In
the second architecture the desiccant simultaneously cools and dehumidifies the air and here the evaporator
of the vapor compression cycle is used only to cool the desiccant. The third is where the desiccant
dehumidifies and only pre-cools the air while the evaporator cools the air in cascade.